1. Field of the Invention
The present invention relates to an electromagnetic shielding structure and a method of manufacturing the electromagnetic shielding structure, and more particularly, to an electromagnetic shielding structure and a manufacturing method thereof that are capable of permanently shielding electromagnetic waves, significantly improving frequency selectivity of electromagnetic waves to be shielded, and being miniaturized and conveniently stored.
2. Description of the Related Art
Various multimedia service environments such as mobile terminals and wireless network environments are quickly increasing all throughout the world. Accordingly, electromagnetic wave-related issues are growing concern. The effect of electromagnetic waves cause enormous losses in terms of the malfunctioning and interference of precision equipment, continuous disruption of power facilities, dangers to human health, leakage of personal information from information devices, etc. Safety standards for electromagnetic waves are being established, and electromagnetic shielding materials are being actively developed in countries around the world. While research on electromagnetic wave shielding in Korea was begun in earnest in late 2002, the importance of strategic infrastructures as well as technical research remain lacking. Thus, the importance of research on electromagnetic wave shielding is growing.
Chemical shielding materials for electromagnetic waves may be classified into shielding paint, shielding fiber, and other materials.
Shielding paints include plastic housing shielding paint, electromagnetic shielding coating material, and electromagnetic wave absorbing/shielding inorganic paint.
Plastic housing shielding paint is formed of material having high conductivity that is applied as a shielding layer on insulating plastic to provide electromagnetic shielding characteristics. However, it is technically difficult to apply plastic as a base to a structure. Electromagnetic shielding coating materials are formed by mixing conductive particles and paint resin, and are applied as a layer to a target structure for shielding electromagnetic waves. Electromagnetic shielding coating materials are useful for electronic devices, homewares, and sundries. However, since electromagnetic shielding coating materials are expensive, their application to construction and civil engineering fields is economically unfeasible. Electromagnetic wave absorbing/shielding inorganic paints include magnetic powder and carbon that absorb/shield electromagnetic waves. Because electromagnetic shielding performance improves with the number of applications, it is difficult to apply electromagnetic wave absorbing/shielding inorganic paints to materials that require high strength, such as concrete.
Shielding fibers include metal film forming fiber, copper compound adhering fiber, conductive resin coating fiber, metal thin film laminating fiber, metal twine fiber, carbon pulp fiber, and shielding Korean paper.
Such a metal film forming fiber includes a metal film obtained by forming conductive material on the surface of a fiber through sputtering or depositing. It is also difficult to apply metal film forming fibers to structures of buildings, such as walls, columns, and beams. A copper compound adhering fiber is formed by adding and adhering copper to a synthetic fiber. A conductive resin coating fiber is formed by coating yarn with a mixture of metal oxide, carbon black, and adhesive. Since both copper compound adhering fiber and conductive resin coating fiber have poor shielding performance, their commercialization is difficult. A metal thin film laminating fiber is formed by laminating a surface of a fiber with a metal thin film. A metal twine fiber is formed by entwining a metal fiber and a typical fiber such as cotton or synthetic fiber.
Although both metal thin film laminating fiber and metal twine fiber have high electromagnetic shielding performance, their fiber characteristics do not render them suitable for applications in structures of buildings. Carbon pulp fibers are flexible, and are thus easily adaptable for uneven surfaces. However, because carbon pulp fibers have poor strength, it is technically difficult to apply them to structures of buildings. Shielding Korean paper is formed of a carbon fiber and a bark fiber from a paper mulberry, and has high electromagnetic shielding performance. However, since such shielding Korean papers are expensive, it is economically difficult to apply them to structures of buildings.
Chemical shielding materials for electromagnetic waves also include shielding tapes, electromagnetic shielding construction materials, shielding screens, and shielding glasses.
Shielding tape is formed by applying a synthetic resin film on a surface of an aluminum thin film, and coating another surface with adhesive. Such a shielding tape is attached to a surface of a target object, and then a synthetic resin film is removed from a shielding tape to provide shielding performance. An electromagnetic shielding construction material, formed by coating a surface of metal thin film with adhesive, is attached to a surface of wall paper. However, the tape characteristics of both a shielding tape and an electromagnetic shielding construction material make it difficult to apply them to structures of buildings. Shielding screens are formed of copper alloy including nickel and tin. Shielding glass is formed of glass including a mesh-shaped metal material having high conductivity. Although both a shielding screen and a shielding glass can be used for expensive electronic appliances or special-purpose products, they are too expensive to be applied to structures of buildings.
Thus, it is difficult to apply the aforementioned chemical electromagnetic shielding materials in large quantities to structures of buildings because of unsuitable properties, difficulties in construction, or economical limitations.
Aside from the aforementioned chemical electromagnetic shielding materials, a physical member formed by periodically disposing protruding blocks on a concreted slab constituting a building, and spacing iron reinforcing rods a predetermined distance in the slab is used to shield/absorb electromagnetic waves.
Such physical electromagnetic shielding members are adapted for noise and low frequency electromagnetic waves. However, since physical electromagnetic shielding members should have minute block structures to shield high frequency electromagnetic waves, frequency selection and construction are difficult to implement.
In addition, electromagnetic waves having specific frequencies are shielded, but electromagnetic waves having wide frequency bands are difficult to shield.
Thus, research has been actively carried out to apply electromagnetic shielding members and methods of manufacturing electromagnetic shielding members to construction fields.
For example, Korean Patent Publication No. 10-2005-0028425 (published on Mar. 23, 2005) discloses a fire-resistant panel for construction, in which inorganic fiber nets are buried between two boards, gauze planes are disposed on retreated parts and projected parts on sides, and fillers fill the inner space between the two boards.
The fire-resistant panel includes the inorganic fiber nets to perform an electromagnetic shielding function and a fireproofing function. However, the electromagnetic shielding function of the inorganic fiber nets is insufficient, and particularly, it is difficult to shield electromagnetic waves having wide frequency bands, and apply the fire-resistant panel to walls or ceilings of buildings, plus, its cost is high.
In addition, Korean Patent Publication No. 10-2003-0034291 (published on May 9, 2003) discloses an electromagnetic shielding material, which includes steel slag, byproducts generated from steel manufacturing, and an electromagnetic shielding material to shield electromagnetic waves.
The electromagnetic shielding material is adapted to recycle slag generated from steel manufacturing. However, it is difficult to shield electromagnetic waves having wide frequency bands, and slag has unsuitable physical properties. Thus, it is difficult to apply the electromagnetic shielding material to walls or ceilings of buildings.
In addition, Korean Patent Publication No. 10-2002-0086025 (published on Nov. 18, 2002) discloses a construction complex product intermixed with amorphous alloy, which is manufactured by weaving the amorphous alloy in a lattice pattern within a mold and filling mortar therein to mold a desired complex product.
The construction complex product intermixed with amorphous alloy has a simple structure, and is inexpensive. However, it is difficult to shield electromagnetic waves having wide frequency bands. In addition, since mortar is filled in the mold for molding, the construction complex product has a low strength. Thus, it is difficult to apply the construction complex product to walls or ceilings of buildings.
In addition, Korean Patent Publication No. 10-2008-0060434 (published on Jul. 2, 2008) discloses an electromagnetic shielding unit and an electromagnetic shielding structure, which selectively shield electromagnetic waves having a specific frequency, and are mixed with concrete.
The electromagnetic shielding unit is adapted to shield electromagnetic waves having a specific frequency. However, when manufacturing a 3-dimensional parallel resonator structure, supports crossing each other in the middle of the structure are difficult to manufacture and expensive. In addition, it takes a long time to manufacture the supports through welding.
In addition, it is difficult for the related art electromagnetic shielding materials to be uniformly disposed in a building. Furthermore, when the related art electromagnetic shielding materials may be removed from a portion of a building over time, a portion of electromagnetic waves passing through a building may not be shielded. Thus, a technology for improving electromagnetic shielding reliability by semi-permanently and uniformly providing an electromagnetic shielding performance to a building is required.